No injuries, heard maybe 20 trucks buried and a couple of loaders (?). http://www.ksl.com/?sid=24748916&nid=148&fm=most_popular&s_cid=article-popular-1
I've seen the photos. Reminds me a bit of the major slip they had in Freeport McMoran's Indonesia operation about 10 years ago. Apparently at Kennecott they'd been monitoring the ground movement for 2 months or so, so they knew it was coming. From the photos I've seen there appears to be about 10 haul trucks and a shovel in one area, a shovel in another, and a boom truck in a 3rd, but that's only what I can see - other stuff may be buried totally out of sight.
http://img.ksl.com//usersubmittedpics/9/920/92059.jpg?filter=ksl/pgallery http://www.ksl.com/?sid=24748916&nid=460&pid=0#6 Hopefully those links work for pictures.
How do you suppose they go about stabilizing and remediating this? It looks like a near vertical face around the top of the slide hundreds of feet high; you couldn't get anything or anybody near it for fear of further collapse.
Start from the top and work down benching it as they go would be my guess. That's what they did at Freeport.
How do they have 2 months to plan for this and still loose several 'Yellow Utes' at the bottom of the pit.
I guess timing of the final collapse came as a bit of a surprise by the sounds of the story and from what I'm hearing on the jungle drums (we have ex-Kennecott people working at our place). The mine has a fleet of around 150 trucks so losing 10 of them (albeit temporarily until they can knock a road down to them and get them out) won't faze them too much I would guess. The mine was still producing all the time since February that first warning came that the slope was moving, and obviously they need trucks & shovels in the pit in order to achieve that. My guess is that they will have been stockpiling ore like it was going out of fashion next to their plant for the last 2 months and that's what they'll be throwing in the primary crusher until they can get ore from the pit again.
One news story I saw says that the slide was larger than they'd anticipated. http://fox13now.com/2013/04/12/bingham-canyon-mine-slide-bigger-than-anticipated/ For those more familiar with how such mines are operated, can I assume most of the material that slid was spoil, from which the good stuff had already been recovered, and overburden? And if so, was it all stacked on undisturbed ground, or do they begin by stacking it on undisturbed ground, and then re-fill the older part of the pit as they move forward into fresh ground?
I read it as the slide travelled further than they anticipated, not necesarily that it was bigger. Usually all the waste from an open pit mine is hauled off to waste dumps beyond the mine boundary. Imagine the mineral deposit as having the shape of a funnel (it was originally a volcano after all) and you chase it from the surface going deeper all the time. As you do the pit boundary at ground level gets wider and wider. I would be surprised if what slipped was "old spoil" unless the mine had moved from one pit to another and built on top of the former spoil dumps. it's not usual but is possible. Not knowing the geology of Kennecott in any detail I couldn't say if that's the case. I would point out that sloughs are part and parcel of open pit mines. I've been personally involved in one in Africa, seen the photos of Freeport in Indonesia, and now seen the photos of this one. All of them involved the movement of major league amounts of material (10+ million tonnes minimum). It's part and parcel of open pit mining. As one mine planning engineer once told me, the perfect mine plan for an open pit is after however many years of mine life that it has, the pit walls collapse just as the last truckload of ore leaves the pit. It's going back to the "funnel" I mentioned before, as you go deeper more waste has to be removed so you steepen up the walls of the pit as much as possible in order to reduce the amount of waste that has to be moved and so keep total costs down. The result of this is (to paraphrase Kevin Costner) - "Some days you win, some days you lose, some days it rains" .............
Nige, I was told the reason for the extra travel distance was that the volume that came down was well in excess of double what they expected.
Studies of major landslides have shown that in extreme circumstances the travel can be up to 20 times the height of the slide. The reason given is that as the rubble moves over the ground it can create a low friction boundary allowing the rubble to maintain its' momentum and energy. The rubble takes on what could be described as fluid characteristics as opposed to its' former solid characteristics and hence the flow. Had there not been an opposing wall to stop the flow that slide would have covered a lot more ground.
I understand what you are saying, but what I was referring to, was the initial projections of the travel distance vs, the actual travel distance being considerable farther due to a much larger area having slid. With the initial projections, a considerably smaller area, and thus smaller height and smaller volume was projected to slide. Only in the last few days, did a larger area begin to slip. At this point it was too late, as there was no safe way to move the equipment further out of harms way. A decision was made to simply abandon what could not be safely moved and hope it weathered the storm, so to speak. Had the initially projected slide occurred, the equipment would have been out of harms way. Had the slippage not shown itself to be considerably larger in the later days before the actual slide occurred, there would likely have been operators still working on the equipment that was still in the pit, and this would have had an entirely different outcome.....and not a good one at that.
I just don't understand how they could get close enough to the edge on top to be able to start taking it down, and not have it slough off and take a machine with it.
I have a feeling they would start at an appropriate distance from the face, and bench their way down. If they were to mine out behind the existing vertical wall, they could drill a line of preshear holes and blast, allowing the material to slough down into the hole as they went.
I think that is one of the reasons the volume to repair a slide is always more than expected. By the time you back off a safe distance, it really adds to the total to be removed. You would never approach anywhere near the recently failed edge.
Two Questions? Could they have used controlled Blasts to relieve the Load earlier and prevent the weight shift momentum? Is there a possibility they will can the OC and wombat the ore out?
One point is cost and if this mine considers the value add to clean up and continue mining or just shutting down all together?
Lots of photos here: https://secure.flickr.com/photos/riotinto-kennecottutahcopper/ I can't tell: was the top of the slide a natural mountain, or was it a tailings pile that failed?
Cat 793 Maybe they could have shot it, But I wouldn't have wanted to be the driller...
I am not sure, but having seen the area I believe that it was not a tailings pile but existing topography that was excavated.
OK, I understand the first question, and I think it was a case of not being allowed to put anyone out on top of the area that was slipping. I'm quite sure MSHA would have gone beyond strange, had they tried that. Basically, the risk wasn't worth it. As for the second question.......can the OC?.....wombat it out?......could you phrase that in English? Like I was saying earlier, I wonder if the material is low grade ore, or straight waste rock? If it's even very low grade ore, it may still be worth processing since it has to be moved anyhow. There are around 20 or so years of mine life left under current plans, so I don't think shutting down is a option. But I wouldn't be surprised if they abandon some of the ore beneath the fallen material, and only excavate the far end of the pit and the wall pushback. Leaving whatever is under the majority of the slide material. Of course, while still stabilizing the slide area. The area that slid was unexcavated rock. There was no spoil piled on the rim of the pit in that location. Just to clarify, tailings is the material that comes out of the tail end of the process at the mill, hence the name. Usually deposited in a pond as it is in a slurry, or dewatered and spread like sand in a disposal area. Waste rock that is piled in a dump is not considered tailings in a hard rock mine.
Alco, you need to understand Strine (Australian) - translated into English he means "Can the Open Cut (OC) and go underground to get the rest of the ore out. - A wombat is an Australian animal that burrows underground. http://en.wikipedia.org/wiki/Wombat
That's why I asked for a translation Nige. Thanks! I doubt they will go that route at this time though, as a good portion of the remaining ore is going to be attained by push backs. I know there is talk of going underground in the future, for deeper ore though.
Just to eliminate any confusion, there is an area behind the slide that is a waste dump, but the slide did not extend into it. I guess the dump is close to the pit rim now though....LOL.
One of the reasons I'd asked my question earlier was that in that series of pictures, and the forth one in particular, there's a spot right in the middle of the slide area that appears to be an un-slid segment of the benched edge of the pit. That, it seemed to me, indicated that the "slid" material was spoil stacked on undisturbed ground. BTW, Nige, thanks for the reply to my question. In my part of the world, the geology is pretty much sedimentary, and the notion of a mineral deposit that was funnel shaped hadn't really occurred to me.
No worries, but that's the reason why most of the world's major open pits are so huge especially if they have been around for 20 years or more. Allegedly some of them like Escondida & Chuquicamata in Chile are visible from outer space. Try locating them on Google Earth and you'll see what I mean.
The name escapes me at the moment (and I'm too lazy to look), but I've done that with that big gold mine in Oz.
I would bet that the mine will continue in nearly full production and at the same time remove much of the slide from the pit or move it to inactive areas. These mines are huge and the investment that has been made at Bingham Canyon in the last years has been huge. Its a productive mine and will continue to be. In fact despite the "Years Long" prediction to remove the waste material, I bet you will find its going to be done much faster than expected. Its expensive to move all tha material, but in the scheme of things at that scale its not all that big a cost. My educated guess only of course. Grasberg had a huge slide and never missed a beat after the first couple weeks.
Not really a fair comparison considering the volume of the Grasberg slide was only 4.1 million, and this one was at least 165 million tons. This is going to take a very long time to clean up. You can't expect to move that much material, in addition to regular production, and expect it to be done quickly without a huge capital outlay for additional equipment or contractors to do the work. Not to mention the infrastructure will struggle to accommodate the additional traffic to do the work. You also have to factor in the slide wall layback, which will have to be done for stability reasons before any of the work can be done below it in the pit.
165 million ton... Shhhhheeeeeeeeeeeeiitt. Our mine doesn't even have that much available to dig, let alone just to slide.
BHP Escondida moves 1.2 million tonnes (1.32m US tons) a day ........ the standing joke was that was despite their on-site management not because of it .......... Digger, you're thinking of KCGM in Kalgoorlie, Australia. Try googling Escondida or Chuquicamata in Chile. Chuqui was started originally by Anaconda minerals in the 50's I think.
Many years ago now, Caterpillar made a film called the "Million Ton Team"...About Phelps-Dodge Morenci Mine..I have a copy. They set a planned record of loading and hauling 1.3 Million tons in 24 hrs.And it was done mainly with 793's at that time. "They had well over 130 -140 trucks" This has been eclipsed of course... in fact quite a few mines move much more. I don't have an idea anymore what the Black Thunder Mine moves in Wyoming in a day, but its incredible. Of course not an open pit operation.
we had a big landslide at our mine last year and all they done was start from the top re-benching it and now they have it back to normal.But we got told from the geo that our mine is 100% cave in failure due to the ground.